In vitro diagnostics (IVD) allows labs to assist in the diagnosis of disease based on assays performed on patient fluid samples. IVD includes various types of analytical tests and assays related to patient diagnosis and therapy that can be performed by analysis of a liquid sample taken from a patient's bodily fluids, or abscesses. These assays are typically conducted with automated clinical chemistry analyzers (analyzers) onto which fluid containers, such as tubes or vials containing patient samples have been loaded. The analyzer extracts a liquid sample from sample vessels and combines the sample with various reagents in special reaction cuvettes or tubes (referred to generally as reaction vessels). In some conventional systems, a modular approach is used for analyzers. A lab automation system can shuttle samples between one sample processing module (module) and another module. Modules may include one or more stations, including sample handling stations and testing stations (e.g., a unit that can specialize in certain types of assays or can otherwise provide testing services to the larger analyzer, which may include immunoassay (IA) and clinical chemistry (CC) stations.
An automation system for use with analyzers in an IVD environment moves tubes containing sample specimens between different stations within an analyzer or between analyzers. One common way to move these samples is by using passive carriers, such as pucks, along a friction track. Commonly, these automation tracks do not provide a large degree of precision when positioning samples. For example, passive pucks may be singulated and positioned mechanically using hard stops within the track. Singulation prongs may hold a puck in place once the puck has traversed the automation track to approximately the needed location. However, these prongs may not be adjustable for each puck and positioning a puck at a hard stop may not necessarily cause samples carried by the pucks to be repeatedly positioned relative to instruments, such as pipettes, along the automation track.
While hard stops may be used to position a puck with relative repeatability, devices that interact with the sample, such as pipettes, may require precise orientation and positioning of the sample at a given location on the track. The position and orientation of each sample may vary relative to the hard stops from puck to puck. For example, the manufacturing tolerances between two pucks may prevent a repeatable location of the bottom of the tube relative to a given singulation point. In addition, tubes may shift within the grasp of a puck, such as by tilting, or moving off center from a holding location within the puck as the puck traverses the automation or at the time an operator places the tube into the puck.
One common way to provide somewhat repeatable positioning of a sample tube employs a holder on a puck with self-centering springs. A self-centering spring mechanism can include three or more springs that provide horizontal forces relative to one another to engage the walls of a sample tube to hold the tube approximately in the center of the mechanism. Self-centering springs may be expensive to manufacture with the tolerances necessary to provide self-centering action. For example, in designs where self-centering springs include multiple springs that push relative to one another, the self-centering action requires the relative forces of the springs to be approximately equal. Furthermore, self-centering springs may only be designed to allow tubes with a relative range of sizes that may be narrower than desired. Self-centering springs may also be poorly suited for maintaining the position of a tube while undergoing large forces as the puck travels around an automation track.
Different hospitals or laboratories may also use different size sample tubes. Within the IVD industry, there may be several standard sizes of available sample tubes. Different laboratories may use a variety of sample tubes or a subset of those available, according to their needs and available inventory. Conventional automation systems have a difficult time using a wide range of available sample tubes. While self-centering springs may allow a range of sample tubes to be used, the effective range of self-centering springs may be limited. In addition, when a range of tubes is used, a typical automation system does not know which size tube is used for each sample. This information can be manually associated with each sample, but requires additional operator steps which may be undesirable.
To determine various properties of samples in sample tubes, various sensors may be used throughout the IVD environment to allow assessment of characteristics important to each instrument. This information is typically sensed in an on-demand basis. For example, a pipette may utilize a liquid level sensor that measures the capacitance or other electrical properties of a pipette tip as it is inserted into a liquid sample during aspiration. A robot arm used in a sample handling unit may include tips that are designed to accept a range of tube diameters. These tips may include sensors or feelers to assist the robot arm in capturing a tube without breaking it. A barcode scanner can be placed at different decision points throughout the IVD environment, allowing a laser-based barcode reader to read information about the identity of each tube once the tube is stopped and rotated to bring a barcode into view of the reader. While the stop-and-check approach to barcode scanning can ensure that each sample is appropriately handled at each decision point, this process may be slow and result in long queues at each decision point.
Accordingly, current methods for handling ranges of sample tube types and for sensing the properties of samples in tubes may be slow or cumbersome, creating a potential bottleneck for increasing throughput or decreasing turn-around-times of samples that are processed by an automation system and related instruments.